Please could some other people try it and feedback if reeve hoban works? He's in the last scenario. Maybe there's just something wrong with my files such that reeve hoban doesn't play

Try re-downloading the add-on from the server. If it doesn't work still than that is a problem enough that something needs to be done. Perhaps some file corruption? It would be bad if half the people have bad voice files...

Via the add-ons menu, I deleted and then redownloaded and installed the Tale of two brothers +voice add-on as well as the sound pack but still when I try playing the last scenario Reeve Hoban's voice over does not play I don't know the reason why.

What I did exactly was to load a replay from the previous scenario, run the replay until near the end and then "continue play" at the point where I can kill the enemy leader and then advance to the last scenario. When advancing, when I get to Reeve Hoban, his voiceover does not play.